1. Field of the Invention
The present invention relates to an image formation apparatus and in particular to an image formation apparatus for making it possible to control the timing of recovery ejection of a nozzle of a print head for executing image formation. The invention also relates to a recovery ejection method of a print head in an image formation apparatus.
2. Background Art
Hitherto, an image formation apparatus for recording an image, etc., on a record medium such as paper while transporting the record medium has been widely used. An ink jet printer widely used among the image formation apparatus forms ink droplets by pressure of piezoelectric elements or thermal foam and ejecting the ink droplets directly onto a record medium from a nozzle of a print head.
Ink in the vicinity of each ink nozzle of a print head increases in viscosity as the volatile component of water content, etc., evaporates and dries over time. In an ink jet printer of an on-demand system for determining whether or not ink is ejected based on record data, the following problem easily occurs particularly in ink nozzles through which ink is ejected less frequently: Ink increases in viscosity and ejection of ink from the print head becomes unstable or it is made impossible to eject ink.
Thus, ejection called flushing or recovery ejection is conducted for expelling ink increased in viscosity from the nozzle aside from ink ejection for forming an image on a record medium.
JP-A-6-15815 discloses an art for flushing on print paper of a record medium. In an ink jet record apparatus disclosed in JP-A-6-15815, when power is turned on, a record head is moved from a standby position to a position facing print paper and ink is ejected from all nozzles, thereby performing flushing.
JP-A-6-15815 also gives a description indicating that a predetermined flushing pattern may be printed instead of ejecting ink from all nozzles.